Receiving device and television receiver

ABSTRACT

A receiving device in which the shielding performance is improved to solve a pulling problem in a receiving device of a direct conversion system is provided.  
     The receiving device includes: a substrate on which an amplifier  30  that amplifies high frequency input signals, a filter  34  that passes only intended signals and removes unintended signals by tuning the amplified high frequency input signals and a direct conversion unit  36  that converts and detects directly the high frequency input signal from the filter; a first high-frequency shielding portion  90  fixed to a substrate  20  and which stands at the boundary between the filter and the other units for preventing radiation of the high frequency electromagnetic wave that is induced from the filter to the space; and a second high-frequency shielding portion  60  provided facing and close to the filter surrounded by the first high-frequency shielding portion  90  and which prevents radiation of high frequency electromagnetic waves induced from the filter to the space, together with the first high-frequency shielding portion  90.

TECHNICAL FIELD

The present invention relates to a receiving device for receiving a highfrequency input signal through a receiving antenna and the televisionreceiver including the receiving device.

BACKGROUND ART

As an example of electronic equipment having a receiving device thatreceives a high frequency input signal, a television receiver can bementioned. The television receiver includes a receiving device thatreceives a high frequency input signal through an antenna.

In a conventional receiving device, a so-called heterodyne system isemployed as shown in FIG. 11.

In the heterodyne system as shown in FIG. 11, a high frequency inputsignal f is input to an antenna 1000. The high frequency input signal fis mixed with a mixing frequency f1 to be selected, so that theintermediate frequency (f−f1) is obtained. Further, after passingthrough a filter or the like, the intermediate frequency (f−f1) is mixedwith a constant frequency f2, and a base band signal ((f−f1)−f2) isobtained. This base band frequency has a range of DC (direct current) toseveral ten MHz.

Note that in this case the relation between f, f1 and f2 is f=f1+f2.

However, the heterodyne system mentioned above requires a large numberof components and frequency conversion of many times, which results in ahigh cost.

Then, as shown in FIG. 12, a direct conversion system having a smallnumber of components and a simple structure is beginning to be used. Inthe direct conversion system, when a high frequency input signal f isinput to an antenna 1010, the mixing frequency f1 which is the same asthe selection frequency is mixed with the high frequency input signal,and the differential signal is taken out to obtain (f−f1) as a base bandsignal.

Note that, in this case, the relationship between f and f1 is f=f1.

In such a receiving device, as shown in FIG. 13, an amplifier 1020, afilter 1024, a direct conversion unit 1026 and a digital demodulator1028 are formed on a substrate 1016. A shield case 1030 and a shieldcover 1040 are detachably loaded onto the substrate 1016, and the shieldcase 1030 and shield cover 1040 shield each elements on the substrate1016 from high frequency waves.

The shield cover 1040 is engaged with ribs 1061 in the shield case 1030,using a plurality of claws 1060 on the peripheral portion thereof to behooked, and the shield cover 1040 and shield case 1030 are contacted andfixed to each other.

The shield case 1030 has a frame 1055, and an inner partition plate 1056is disposed in the center of the frame 1055. The frame 1055 has aplurality of claws 1050, and when the claws 1050 are fixed into concaveportions 1017 in the substrate 1016, the shield case 1030 is fixed tothe substrate 1016.

With the above structure, the amplifier 1020, the filter 1024, thedirect conversion unit 1026 and the digital demodulator 1028, each ofwhich is a functional block of the substrate 1016, are surrounded andshielded.

The inner partition plate 1056 of the shield case 1030 is, for example,disposed to shield between the filter 1024 and the direct conversionunit 1026, where the partition plate 1056 is soldered to the ground ofthe substrate 1016 to function as a shield plate.

DISCLOSURE OF THE INVENTION

However, with the structure of the conventional shield cover 1040 andshield case 1030, a gap is generated between the partition plate 1056and the shield cover 1040, and thus, the higher the frequency of highfrequency input signal becomes, the more the electromagnetic wave ofhigh frequency leaks from the gap between the partition plate 1056 andthe shield cover 1040 to reduce the effectiveness of shielding.

Also, when it is seen from the viewpoint of high frequency, with respectto the inner partition plate 1056 the ground impedance is lowest at theportion soldered with the ground of the substrate 1016; however, theground impedance of a portion of the shield case which is far from theinner partition plate 1056 becomes high.

With respect to the shield cover 1040, a plurality of claws 1060 and aspring-shaped weight 1070 in the shield cover 1040 are only in contactwith the shield case 1030 side, and the other portions of the shieldcover and shield case are not contacted; thus, no other portion than theplurality of claws 1060 and the spring-shaped weight 1070 is providedwhere the ground impedance becomes low.

High frequency electric current is easily induced at the portion wherethe ground impedance is high, and with the induced current the highfrequency energy may again radiate into the space, so that efficientshielding can not sufficiently be obtained when a conventional shieldcover and shield case are used.

In a receiving device having a direct conversion system, the highfrequency input signal f which is the receiving signal, is the same asthe local frequency f1 as mentioned above, and in the case that thehigh-frequency input signal with a strong signal level is inputted intoa input unit of a receiving device, the high frequency energy becomeshighly strong at the initial stage amplifier 1020 and also at the filter1024 of a sub-tuning band-pass filter and others. Particularly, highfrequency energy is easily radiated from the filter 1024 due to the Qvalue of a circuit in the substrate 1016. The problem (of so-calledpulling) that this radiated energy affects the local frequency ofselection unit occurs in a receiving device employing the directconversion system.

In light of the above, the present invention aims to provide a receivingdevice and a television receiver, in which the above problem is solvedand the shielding performance is improved to solve the pulling problemin the receiving device employing the direct conversion system.

The present invention is a receiving device including: a substrateprovided with an amplifier that amplifies a high frequency input signal,a filter that passes only an intended signal and a detector that detectsan output signal from the filter, having a land of the referencepotential in the vicinity of a hole bored at the boundary between thefilter of the substrate and the surrounding area thereof; a shield casehaving a shield plate portion made of a metal plate and a projectionthat is inserted into the hole of the substrate and is connected to aland of the reference potential by soldering, in which the filter issurrounded by the shield plate portion; and a metal shield cover thatcovers the shield plate portion of the shield case.

Accordingly, in the state in which the projection of the shield case issoldered with the land of the reference potential of the substrate, ashield case made to stand on the boundary between the filter and theother units can surround the filter. In addition, a shield cover isdisposed to cover the shield case and prevents the leakage of radiationof high frequency electro-magnetic waves generated from the filter intothe space, so that the pulling problem in a receiving device having thedirect conversion system can be solved.

In the above mentioned receiving device according to the presentinvention, the above shield cover has: a main surface, a part of whichis deeply bent to form a dropped-lid shape and which covers the filter,and a first surface-contact portion and a second surface-contact portionformed to oppose to each other on both end portions of the main surface,which stand up from the main surface portion with a predetermined heightand are disposed to come in surface contact with the shield plateportion of the shield case; in which the first surface-contact portionis provided at the boundary between the main surface portion and aportion that is not deeply bent of the shield cover.

Accordingly, since the shield cover is in surface contact with theshield plate portion of the shield case with the first and secondsurface-contact portions, the effectiveness of shielding of thesubstrate can further be improved.

In the above mentioned receiving device according to the presentinvention, the second surface-contact portion of the shield cover isformed to have an angle larger than a right angle with respect to themain surface portion.

Accordingly, when covering the shield case, the shield cover can beprevented from pulling off.

The present invention is a television receiver having the abovementioned receiving device, further including: a digital demodulatorthat demodulates a transport stream from an output of a detector, a dataseparator that separates compressed data of the desired program fromdata multiplexed in the transport stream from the digital demodulator,an MPEG demodulator that expands a compressed data of the program fromthe data separator, an image processor that converts the expanded datafrom the MPEG demodulator into a video output signal, and a display thatdisplays the video output signal from the image processor.

In the television receiver according to the present invention, thesubstrate has an amplifier that amplifies a high frequency input signal,a filter that passes only an intended signal and removes an unintendedsignal by tuning the amplified high frequency input, and a detector thatperforms direct conversion on the high frequency input signal from afilter to be detected.

In the state in which a projection of a shield case is soldered with aland of the reference potential, the shield case stands at the boundarybetween a filter and the other unit to surround the filter. A shieldcover is disposed to cover the filter surrounded by the shield case. Theshield cover prevents the leakage of radiation of high frequencyelectromagnetic waves from the filter into the space.

Accordingly, the pulling problem in a receiving device having the directconversion system can be solved.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram showing an example of electronic equipmentincluding a receiving device according to the present invention;

FIG. 2 is a perspective view showing an example of the construction ofthe receiving device of FIG. 1;

FIG. 3 is a view showing the state in which a shield cover is removedfrom the receiving device of FIG. 2;

FIG. 4 is a perspective view showing only the shield cover;

FIGS. 5A to 5C are sectional views showing an example of theconstruction of a shield cover, a shield case, and a substrate;

FIG. 6 is a view showing the construction of a shield cover;

FIGS. 7A and 7B are views showing the construction of a shield cover;

FIG. 8 is a view showing an example of the shape of the dropped-lidportion of a shield cover;

FIG. 9 is a perspective view showing another embodiment of the receivingdevice according to the present invention;

FIG. 10 is a view showing an example of the cross section of a shieldcover, a shield case and a substrate of a receiving device of FIG. 9;

FIG. 11 is a drawing showing a conventional heterodyne system;

FIG. 12 is a drawing showing a direct conversion system; and

FIG. 13 is an exploded perspective view showing a conventional receivingdevice.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be explained indetail with reference to the accompanying drawings.

It should be noted that embodiments mentioned hereinafter are thepreferred examples and thus the technically preferred variouslimitations are given thereto; however, the scope of the presentinvention is not limited to those embodiments as long as there is nomention of limiting the present invention in the following explanation.

FIG. 1 shows a television receiver as an example of electronic equipmenthaving a receiving device according to the present invention.

A television receiver 14 includes a receiving device 10, a dataseparator 42, an MPEG demodulator 44, an image processor 46 and adisplay 48. The receiving device 10 has a substrate 20 (also call acircuit board), and the substrate 20 has an amplifier 30, a filter 34, adirect conversion unit 36 and a digital demodulator 40.

The amplifier 30, the filter 34, the direct conversion unit 36 and thedigital demodulator 40 are the functional blocks formed on the substrate20. The amplifier 30 is connected to a receiving antenna through aconnector 90A, and the receiving antenna receives a high frequency inputsignal f. The high frequency input signal f is amplified in theamplifier 30. The filter 34 makes the amplified high frequency inputsignal tuned to pass only an intended signal and also to remove anunintended signal, and the filter 34 generates a tuning frequency (alocal frequency) f1.

The direct conversion unit 36 generates a base band (f−f1) bysubtracting a local frequency f1 generated in the filter 34 from thehigh frequency input signal f. Specifically, the direct conversion unit36 has a function of tuning the amplified high frequency input signal fto a local frequency f1 generated in the filter 34 to convert directlyand detect.

The digital demodulator 40 has a function of demodulating a transportstream from a modulated digital signal.

A data separator 42 performs in a unit of packets filtering of videoinformation, audio information, program specifying information, programarrangement information, data broadcast information, and others whichare multiplexed with a digitally demodulated transport stream, toseparate and select compressed data of the desired program.

The MPEG demodulator 44 expands compressed data of the program separatedby the data separator 42. The image processor 46 outputs a video outputsignal from the expanded data by the MPEG demodulator 44, and displaysan image on the display 48 of a plasma display or the like, for example.Also, audio information is processed in an audio processor not shown inthe drawing to be output from a speaker or the like.

FIG. 2 shows an embodiment of the receiving device 10 of FIG. 1.

The receiving device 10 has a substrate 20, a shield cover 60 and ashield case 90.

The shield cover 60 and the shield case 90 are made of, for example,metal such as aluminum that can prevent the leakage of a high frequencyelectromagnetic wave. The shield cover 60 covers the shield case 90 andis detachably attached thereto. The shield case 90 is attacheddetachably to the substrate 20.

FIG. 3 shows the state in which only the shield case 90 is installed onthe substrate 20, and the shield cover 60 is removed from the shieldcase 90. FIG. 4 shows the structure of the shield cover 60.

FIG. 5A shows an example of the shape of cross section on A-A line ofFIG. 2. As shown in FIG. 5A, the amplifier 30, the filter 34, the directconversion unit 36 and the digital demodulator 40 are formedsequentially on the one side surface of the substrate 20.

FIG. 5B shows the state in which projections 170 of the shield case 90are inserted into holes 173 of the substrate 20, and soldered.

Also, FIG. 5C shows the other side surface of the substrate 20, in whichthe projections 170 of the shield case 90 are inserted into the holes173 of the substrate 20, though not yet soldered.

As shown in FIG. 5C, a ground pattern 171 is formed on almost whole thesurface on the other side surface of a substrate 20; rounds 175 areprovided around the holes 173 of the substrate 20; the rounds 175 andprojections 170 of the shield case 90 are soldered to fix the shieldcase 90 and the shield case 90 is electrically connected to the groundpattern 171; and thus, the shield case 90 can be grounded.

By covering the shield case 90 with the shield cover 60, the leakage ofradiation of high frequency generated from the filter into the space isefficiently prevented.

First, the structure of the shield case 90 will be explained withreference to FIGS. 2 and 3.

The shield case 90 is formed by bending and punching out, for example,an aluminum plate, which corresponds to the first high-frequencyshielding portion. On the other hand, the shield cover 60 corresponds tothe second high-frequency shielding portion.

In order to prevent the radiation of high frequency electro magneticwaves into the space from each of the amplifier 30, filter 34 and directconversion unit 36 which are functional blocks on the substrate 20 asshown in FIG. 5, the shield case 90 functioning as the firsthigh-frequency shielding portion is formed to surround the abovementioned amplifier 30, filter 34 and direct conversion unit 36.

As shown in FIG. 3, the shield case 90 has a first frame 100 thatsurrounds the amplifier 30, a second frame 101 that surrounds the filter30 and a third frame 102 that surrounds the direct conversion unit 36.The first frame 100, the second frame 101 and the third frame 102 arecontinuously formed.

The first frame 100 is formed to stand at the boundary between theamplifier 30 and the other units and to surround the amplifier 30,having side surface portions 110, 111, 112 and 113. Similarly, thesecond frame 101 is formed to stand at the boundary between the filter34 and the other units and to surround the filter 34, having a firstshield plate portion 115, a second shield plate portion 117, a thirdshield plate portion 118 and a fourth shield plate portion 119.

The side surface portion 110 and the side surface portion 113 of thefirst frame 100 oppose to each other as shown in FIG. 3, and also theside surface portion 111 and the side surface portion 112 oppose to eachother. Those four side surface portions 110 to 113 are formed to standto separate the amplifier 30 and the filter 34 that is the other unit.

The first shield plate portion 115 and the second shield plate portion117 of the second frame 101 oppose to each other, and also the thirdshield plate portion 118 and the fourth shield plate portion 119 opposeto each other. The first shield plate portion 115 is formed to stand atthe first boundary between the amplifier 30 and the filter 34. Thesecond shield plate portion 117 is formed to stand at the secondboundary between the filter 34 and the direct conversion unit 36.

The third shield plate portion 118 and the fourth shield plate portion119 are formed to stand between the filter 34 and the outside.Accordingly, the second frame 101 is formed to stand at the boundariesof four corners of a rectangular-shaped filter 34 so that high frequencyelectromagnetic waves can be shielded. Note that the side surfaceportion 113 and the first shield plate portion 115 are formed of theportion used in common.

Next, as shown in FIG. 3, the third frame 102 has side surface portions130, 131, 132 and 133 to surround the direct conversion unit 36. Theside surface portions 130 and 132 oppose to each other, and the sidesurface portions 131 and 133 also oppose to each other. The side surfaceportion 130 is disposed at the boundary between the filter 34 and thedirect conversion unit 36. The side surface portion 132 is disposed tostand at the boundary between the direct conversion unit 36 and thedigital demodulator 40. The side surface portion 131 and a side surfaceportion 133 are provided to stand at the boundary between the directconversion unit 36 and the outside. Further the side surface portion 130and the second shield plate portion 117 are formed of the portion usedin common.

In addition, on the four side surfaces of the shield case 90 functioningas the first high-frequency shielding portion as shown in FIG. 3, ribs150 are formed with a projection in the directions parallel to the X andY directions of the substrate 20. FIG. 3 shows a pair of ribs 150 and150 at the front side, and also the same ribs 150 and 150 are formed onthe two surfaces of the rear side.

Further, as shown in FIG. 5A, the shield case 90 has a plurality ofprojections 170 on the first shield plate portion 115 and the secondshield plate portion 117. As shown in FIGS. 5B and 5C, those projections170 are inserted into the holes 173 formed on the substrate 20 and aregrounded by being soldered with the lands of the ground pattern providedclose to the holes 173; and the shield case 90 is attached to thesubstrate 20 through the projections 170.

Next, the structure of the shield cover 60 as the second high-frequencyshielding portion is explained with reference to FIGS. 2, 4 and 6.

The shield cover 60 is formed by bending metal such as aluminum or thelike, for example, and is a member having an almost rectangular shape.As shown in FIG. 2, the shield cover 60 covers a shield case 90 shown inFIG. 3 and is fixed detachably.

The shield cover 60 is jointly used with the shield case 90 as the firsthigh-frequency shielding portion to prevent the leakage of radiation inthe space from the amplifier 30, the filter 34, the direct conversionunit 36 and the digital demodulator 40. Particularly, as shown in FIG.SA, the main surface portion 200 of the shield cover 60 comes close tothe surface and covers the filter 34. Accordingly, high frequencyelectromagnetic waves generated in the filter 34 and radiated to theoutside can be prevented completely.

Schematically explained, the shield cover 60 in FIG. 2 has a frame 201,the main surface portion 200, a first surface-contact portion 202, asecond surface-contact portion 203, a hole 204 and the like.

The frame 201 is formed of a rectangular shape, and as shown in FIG. 6,a plurality of claws 220, 230, 240 and 250 are formed downward on thosefour side surfaces. FIG. 7A shows a cross section of C-C line in FIG. 6,and FIG. 7B shows a cross section of B-B line in FIG. 6.

As shown in FIG. 6(A) and FIG. 2, the first surface-contact portion 202,the second surface-contact portion 203 and the main surface portion 200are formed by bending a double-sided surface portion 206 of the frame201 to have a dropped-lid shaped portion 210.

As shown in FIG. 5A, the dropped-lid shape portion 210 is provided atthe position facing the filter 34. Then, the first surface-contactportion 202 is bent at right angles with respect to the surface portion206, the main surface portion 200 is further bent at right angles withrespect to the first surface-contact portion 202, and furthermore thesecond surface-contact portion 202 is bent at right angles with respectto the main surface portion 200. Therefore, the dropped-lid shapeportion 210 has almost a U-shape when seeing the cross section thereof.

The inside surface of the first surface-contact portion 202 is insurface contact with the outside surface of the first shield plateportion 115 of the shield case 90. The inside surface of the secondsurface-contact portion. 203 is in surface contact with the outsidesurface of the second shield plate portion 117 of the shield case 90.

Further, the main surface portion 200 faces the position of the filter34 where a small gap is provided, namely, the main surface portion comesclose to the filter.

Accordingly, high frequency electromagnetic waves generated from thefilter 34 can be prevented completely from radiating into the space tothe outside, using the first shield plate portion 115, the second shieldplate portion 117, the third shield plate portion 118 and the fourthshield plate portion 119 shown in FIG. 3 and the main surface portion200, the first surface-contact portion 202 and the secondsurface-contact portion 203 shown in FIG. 5A.

As shown in FIG. 5A, the end portion of the second surface-contactportion 203 becomes an L-shaped bent portion 203A and this bent portion203A comes in contact with the upper end surface of the second shieldingportion 117. Accordingly, the main surface portion 200 can be positionedand disposed in parallel with respect to the filter 34 in the state offacing close thereto. The shield case 90 has a connector to connect toan antenna 45.

The hole 204 is formed facing the position of the direct conversion unit36.

As shown in FIGS. 2 and 6, the shield cover 60 has the above mentionedclaws 220, 230, 240 and 250, and the shield cover 60 can be fixeddetachably to cover the shield case 90 with engaging those claws withthe ribs 150 of the shield case 90 in FIG. 2 that is formed at thecorresponding position.

As described above, a receiving device of the embodiment of the presentinvention uses a so-called direct conversion system, in which the filter34 having a sub-tuning band pass filter and others may secondarilyradiate larger high-frequency energy in comparison with the other unitsin the receiving device.

Therefore, in the embodiment shown in FIG. 2, the shield case 90 andshield cover 60 have the structure in which not only the filter 34 thatradiates the highest high frequency energy secondarily, but also theamplifier 30 and the direct conversion unit 36 as shown in FIG. 5A canbe shielded.

Particularly, the shield cover 60 and shield case 90 are provided withthe dropped-lid shaped portion 210 as mentioned above with respect tothe filter 34 which generates the highest high-frequency energy (highfrequency electromagnetic waves); and the first surface-contact portion202, the second surface-contact portion 203 and the main surface portion200 of the dropped-lid shaped portion 210 of the shield cover 60 and thefirst shield plate portion 115, the second shield plate portion 117, thethird shield plate portion 118 and the fourth shield plate portion 119of the shield case 90 shown in FIG. 3 are combined to be used, so thatthe radiation of the high frequency energy to the outside space from thefilter 34 can be prevented.

As shown in FIG. 5A, since the structure in which the firstsurface-contact portion 202 is in surface contact with the first shieldplate portion 115 and also the second surface-contact portion 203 is insurface contact with the second shield plate portion 117 is used, a gapbetween the shield cover 60 and the shield case 90 occurred on thefilter 34 can be prevented and the leakage of high frequencyelectromagnetic waves induced in the filter 34 can be prevented.

The shield cover 60 and the shield case 90 are in surface contact usingthe first surface-contact portion 202 and the second surface-contactportion 203 of the dropped-lid shaped portion 210, and the first shieldplate portion 115 and the second shield plate portion 117 of a shieldcase 90. Accordingly, the strong surface-contact portion between theshield cover 60 and the second shield plate portion 117 as the partitionplate can be constructed close to the position where the second shieldplate portion 117 having the lowest impedance with respect to highfrequency and the ground of the substrate 20 are soldered. Therefore, aground impedance of the shield cover 60 can be greatly reduced.Consequently, the induction of high frequency current can be reduced byobtaining the decrease in ground impedance; as a result, there-radiation of high frequency electromagnetic waves can be reducedgreatly.

In the embodiment shown in FIG. 2, the shield cover 60 as the secondhigh-frequency shielding portion has dimensions that can cover all theshield case 90.

As shown in FIG. 8, the second surface-contact portion 203 of adropped-lid shaped portion 210 is formed with tilt by θ as shown in FIG.8 in the released state. In this state, as shown in FIG. 5A, thedropped-lid shaped portion 210 is inserted by force into the portionbetween the first shield plate portion 115 and the second shield plateportion 117 of the shield case 90, so that the dropped-lid shapedportion 210 may not be detached from the shield case 90 using anelasticity of the second surface-contact portion 203.

FIGS. 9 and 10 show another embodiment of the present invention.

In the embodiment shown in FIGS. 9 and 10, a shield cover 360 as thesecond high-frequency shielding portion is made smaller in comparisonwith the shield cover 60 shown in FIG. 2. The shield cover 360 isattached to the ribs 150 of the shield case 90 using the claws 220.

The shield cover 360 has the structure only facing the filter 34 asshown in FIG. 10. The shield case 90 shown in FIGS. 9 and 10 can use thesame structure of the shield case 90 shown in FIG. 2. Also, thesubstrate 20 is the same as that shown in FIG. 2.

The shield cover 360 has a frame 301 and a dropped-lid shaped portion310. The dropped-lid shaped portion 310 has the first surface-contactportion 202, the second surface-contact portion 203 and the main surfaceportion 200. Therefore, the structure of the dropped-lid shaped portion310 is almost the same as the dropped-lid shaped portion 210 shown inFIG. 2.

As shown in FIG. 10, the first shield plate portion 115 is in surfacecontact with the first surface-contact portion 202. Similarly, thesecond shield plate portion 117 is in surface contact with the secondsurface-contact portion 203. The main surface portion 200 faces thefilter 34 having a small space in between.

The shield cover 360 can be small-sized using such structure, andparticularly the radiation from the filter 34 which secondarily induceshigh frequency electromagnetic waves can be prevented.

According to the embodiments of the present invention, the shieldingperformance in a filter which particularly radiates high frequencyelectromagnetic waves secondarily in a receiving device of a so-calleddirect conversion system can be improved, so that the pulling problem ina receiving device of the direct conversion system can be solved.

Even if there is electromagnetic wave disturbance from the outside of areceiving device, penetration of the electro-magnetic waves can bereduced with the improvement in shielding performance.

Since a shield cover has a dropped-lid shaped portion, when assembling ashield cover and a shield case, the positions of a shield cover and ashield case can be easily determined mutually using the dropped-lidshaped portion, and consequently assembly can be performed easily toimprove the assembling operation efficiency.

According to the embodiments of the present invention, in a receivingdevice of a direct conversion system, radiation of high frequencyelectromagnetic waves from a filter to the space can be reduced bydisposing a dropped-lid shaped portion with respect to the filter in thecase where an amplifier (amplifier circuit unit) and a subsequent filter(also called filter circuit unit) are covered by a shield cover.

It should be noted that the present invention is not limited to theabove mentioned embodiments.

In the above mentioned embodiments, a receiving device is installed in atelevision receiver as an example of electronic equipment. However, areceiving device of the present invention is not limited thereto and canalso be applied to the other types of electronic equipment.

1-5. (canceled)
 6. A receiving device comprising; a substrate providedwith an amplifier that amplifies a high frequency input signal, a filterthat passes only an intended signal after tuning the high frequencyinput signal amplified by said amplifier, and a direct conversion unitin which the high frequency input signal from said filter is mixed witha local frequency signal having the same frequency to obtain a base bandsignal that is a differential signal, having a land of the referencepotential around a hole that is used for a shield case and that isprovided around said filter; a shield case that is formed of a metalplate and that surrounds said amplifier, filter and direct conversionunit, having a frame that surrounds said filter and a projection that isformed on said frame and that is inserted into the hole formed on saidsubstrate, in which said projection is connected to said land of thereference potential by soldering; and a metal shield cover that coversat least the frame surrounding said filter and that has a dropped-lidshape to come close to said filter.
 7. A receiving device according toclaim 6, wherein a digital demodulator that demodulates a transportstream from an output of said direct conversion unit is further providedon said substrate.
 8. A receiving device according to claim 6, whereinsaid shield cover has a dropped-lid shaped portion that is bent to formthe dropped-lid shape and a frame that is formed by bending saiddropped-lid shaped portion; and said dropped-lid shaped portion has amain surface portion that covers said filter, a first surface-contactportion formed between the main surface portion and said frame to be insurface contact with said frame, and a second surface-contact portionformed opposing to the first surface contact portion to be in surfacecontact with said frame.
 9. A receiving device according to claim 8,wherein said second surface-contact portion is formed at an angle of notdetaching from said shield case, when covering said shield case.
 10. Atelevision receiver including a receiving device according to claim 6,further comprising: a digital demodulator that demodulates a transportstream from an output of said detector; a data separator that separatescompressed data of the desired program from data multiplexed in thetransport stream from said digital demodulator; an MPEG demodulator thatexpands the compressed data of the desired program from said dataseparator; an image processor that converts the expanded data from saidMPEG demodulator to a video output signal; and a display that displays avideo output signal from said image processor.